jismesh 0.2.0

Utilities for handling and converting JIS X0410 area mesh codes.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340

use super::*;

/// Applies a base level adjustment to latitude and longitude
fn apply_base_adjustment(idx: usize, ab: &[u8], cd: &[u8], lat: &mut [f64], lon: &mut [f64]) {
    lat[idx] = ab[idx] as f64 * UNIT_LAT_LV1;
    lon[idx] = cd[idx] as f64 * UNIT_LON_LV1 + 100.0;
}

/// Applies the level 40000 adjustment to latitude and longitude
fn apply_level_40000(idx: usize, e: &[u8], lat: &mut [f64], lon: &mut [f64]) {
    if e[idx] / 3 == 1 {
        lat[idx] += UNIT_LAT_40000;
    }
    if e[idx] % 2 == 0 {
        lon[idx] += UNIT_LON_40000;
    }
}

/// Applies the level 2 adjustment to latitude and longitude
fn apply_level_2(idx: usize, e: &[u8], f: &[u8], lat: &mut [f64], lon: &mut [f64]) {
    lat[idx] += e[idx] as f64 * UNIT_LAT_LV2;
    lon[idx] += f[idx] as f64 * UNIT_LON_LV2;
}

/// Applies the level 3 adjustment to latitude and longitude
fn apply_level_3(
    idx: usize,
    e: &[u8],
    f: &[u8],
    g: &[u8],
    h: &[u8],
    lat: &mut [f64],
    lon: &mut [f64],
) {
    // First apply level 2 component
    apply_level_2(idx, e, f, lat, lon);

    // Then add level 3 component
    lat[idx] += g[idx] as f64 * UNIT_LAT_LV3;
    lon[idx] += h[idx] as f64 * UNIT_LON_LV3;
}

/// Applies the level 4 adjustment which builds on level 3
fn apply_level_4(
    idx: usize,
    e: &[u8],
    f: &[u8],
    g: &[u8],
    h: &[u8],
    i: &[u8],
    lat: &mut [f64],
    lon: &mut [f64],
) {
    // First apply level 3 component
    apply_level_3(idx, e, f, g, h, lat, lon);

    // Then add level 4 component
    if i[idx] / 3 == 1 {
        lat[idx] += UNIT_LAT_LV4;
    }
    if i[idx] % 2 == 0 {
        lon[idx] += UNIT_LON_LV4;
    }
}

/// Applies the level 5 adjustment which builds on level 4
fn apply_level_5(
    idx: usize,
    e: &[u8],
    f: &[u8],
    g: &[u8],
    h: &[u8],
    i: &[u8],
    j: &[u8],
    lat: &mut [f64],
    lon: &mut [f64],
) {
    // First apply level 4 component
    apply_level_4(idx, e, f, g, h, i, lat, lon);

    // Then add level 5 component
    if j[idx] / 3 == 1 {
        lat[idx] += UNIT_LAT_LV5;
    }
    if j[idx] % 2 == 0 {
        lon[idx] += UNIT_LON_LV5;
    }
}

/// Applies the final multiplier adjustments
fn apply_multipliers(
    idx: usize,
    level: MeshLevel,
    lat_multiplier: &[f64],
    lon_multiplier: &[f64],
    lat: &mut [f64],
    lon: &mut [f64],
) {
    lat[idx] += unit_lat(level) * lat_multiplier[idx.min(lat_multiplier.len() - 1)];
    lon[idx] += unit_lon(level) * lon_multiplier[idx.min(lon_multiplier.len() - 1)];
}

/// Calculates a mesh point (latitude, longitude) from a meshcode and multipliers.
pub fn to_meshpoint(
    meshcode: &[u64],
    lat_multiplier: &[f64],
    lon_multiplier: &[f64],
) -> Result<Vec<Vec<f64>>> {
    // Convert single values to arrays
    let meshcode_len = meshcode.len();

    // Get the mesh level for each code
    let level = to_meshlevel(meshcode)?;

    // Extract parts from meshcode
    let ab = slice(meshcode, 0, 2);
    let cd = slice(meshcode, 2, 4);
    let e = slice(meshcode, 4, 5);
    let f = slice(meshcode, 5, 6);
    let g = slice(meshcode, 6, 7);
    let h = slice(meshcode, 7, 8);
    let i = slice(meshcode, 8, 9);
    let j = slice(meshcode, 9, 10);
    let k = slice(meshcode, 10, 11);

    // Initialize lat and lon vectors
    let mut lat = vec![0.0; meshcode_len];
    let mut lon = vec![0.0; meshcode_len];

    // Process coordinates based on mesh levels
    for idx in 0..meshcode_len {
        // Start with level 1 coordinates (base for all mesh levels)
        apply_base_adjustment(idx, &ab, &cd, &mut lat, &mut lon);

        match level[idx] {
            // Level 1 - already handled in apply_base_adjustment
            MeshLevel::Lv1 => {}

            // Level 40000
            MeshLevel::X40 => {
                apply_level_40000(idx, &e, &mut lat, &mut lon);
            }

            // Level 20000
            MeshLevel::X20 => {
                // Add level 40000 component
                apply_level_40000(idx, &e, &mut lat, &mut lon);

                // Add level 20000 component
                if f[idx] / 3 == 1 {
                    lat[idx] += UNIT_LAT_20000;
                }
                if f[idx] % 2 == 0 {
                    lon[idx] += UNIT_LON_20000;
                }
            }

            // Level 16000
            MeshLevel::X16 => {
                lat[idx] += (e[idx] / 2) as f64 * UNIT_LAT_16000;
                lon[idx] += (f[idx] / 2) as f64 * UNIT_LON_16000;
            }

            // Level 8000
            MeshLevel::X8 => {
                lat[idx] += e[idx] as f64 * UNIT_LAT_8000;
                lon[idx] += f[idx] as f64 * UNIT_LON_8000;
            }

            // Level 4000
            MeshLevel::X4 => {
                // Add level 8000 component
                lat[idx] += e[idx] as f64 * UNIT_LAT_8000;
                lon[idx] += f[idx] as f64 * UNIT_LON_8000;

                // Add level 4000 component
                if h[idx] / 3 == 1 {
                    lat[idx] += UNIT_LAT_4000;
                }
                if h[idx] % 2 == 0 {
                    lon[idx] += UNIT_LON_4000;
                }
            }

            // Level 2
            MeshLevel::Lv2 => {
                apply_level_2(idx, &e, &f, &mut lat, &mut lon);
            }

            // Level 5000
            MeshLevel::X5 => {
                // Add level 2 component
                apply_level_2(idx, &e, &f, &mut lat, &mut lon);

                // Add level 5000 component
                if g[idx] / 3 == 1 {
                    lat[idx] += UNIT_LAT_5000;
                }
                if g[idx] % 2 == 0 {
                    lon[idx] += UNIT_LON_5000;
                }
            }

            // Level 2500
            MeshLevel::X2_5 => {
                // Add level 2 component
                apply_level_2(idx, &e, &f, &mut lat, &mut lon);

                // Add level 5000 component
                if g[idx] / 3 == 1 {
                    lat[idx] += UNIT_LAT_5000;
                }
                if g[idx] % 2 == 0 {
                    lon[idx] += UNIT_LON_5000;
                }

                // Add level 2500 component
                if h[idx] / 3 == 1 {
                    lat[idx] += UNIT_LAT_2500;
                }
                if h[idx] % 2 == 0 {
                    lon[idx] += UNIT_LON_2500;
                }
            }

            // Level 2000
            MeshLevel::X2 => {
                // Add level 2 component
                apply_level_2(idx, &e, &f, &mut lat, &mut lon);

                // Add level 2000 component
                lat[idx] += (g[idx] / 2) as f64 * UNIT_LAT_2000;
                lon[idx] += (h[idx] / 2) as f64 * UNIT_LON_2000;
            }

            // Level 3
            MeshLevel::Lv3 => {
                apply_level_3(idx, &e, &f, &g, &h, &mut lat, &mut lon);
            }

            // Level 4
            MeshLevel::Lv4 => {
                apply_level_4(idx, &e, &f, &g, &h, &i, &mut lat, &mut lon);
            }

            // Level 5
            MeshLevel::Lv5 => {
                apply_level_5(idx, &e, &f, &g, &h, &i, &j, &mut lat, &mut lon);
            }

            // Level 6
            MeshLevel::Lv6 => {
                // First apply level 5 component
                apply_level_5(idx, &e, &f, &g, &h, &i, &j, &mut lat, &mut lon);

                // Then add level 6 component
                if k[idx] / 3 == 1 {
                    lat[idx] += UNIT_LAT_LV6;
                }
                if k[idx] % 2 == 0 {
                    lon[idx] += UNIT_LON_LV6;
                }
            }
        }

        // Add multiplier adjustments
        apply_multipliers(
            idx,
            level[idx],
            lat_multiplier,
            lon_multiplier,
            &mut lat,
            &mut lon,
        );
    }

    // Create a vector of [lat, lon] pairs for each meshcode
    Ok(vec![lat, lon])
}

#[cfg(test)]
mod tests {
    use super::*;
    use approx::assert_relative_eq;

    #[test]
    fn test_to_meshpoint() {
        // Test cases mirroring the Python test data
        let test_cases = vec![
            // (meshcode, lat_multiplier, lon_multiplier, expected_lat, expected_lon)
            (5339u64, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (53391, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (5339115, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (5339007, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (533900, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (5339006, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (5339001, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (533900617, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (533900116, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (533900005, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (53390000, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (533900001, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (5339000011, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (53390000111, 0.0, 0.0, 35.0 + 1.0 / 3.0, 139.0),
            (53393599212, 0.5, 0.5, 35.6588542, 139.74609375),
        ];

        for (meshcode, lat_multiplier, lon_multiplier, expected_lat, expected_lon) in test_cases {
            // Call the function
            let result = to_meshpoint(&[meshcode], &[lat_multiplier], &[lon_multiplier]).unwrap();

            // Check results with approximately equal (7 decimal places)
            assert_relative_eq!(result[0][0], expected_lat, epsilon = 1e-7);
            assert_relative_eq!(result[1][0], expected_lon, epsilon = 1e-7);
        }
    }

    #[test]
    fn test_to_meshpoint_vector() {
        // Test with vector inputs
        let num_elements = 10;
        let meshcode_value = 53390000111;
        let expected_lat = 35.0 + 1.0 / 3.0;
        let expected_lon = 139.0;

        // Call the function
        let result = to_meshpoint(
            &vec![meshcode_value; num_elements],
            &vec![0.0; num_elements],
            &vec![0.0; num_elements],
        )
        .unwrap();

        // Check results
        for i in 0..num_elements {
            assert_relative_eq!(result[0][i], expected_lat, epsilon = 1e-7);
            assert_relative_eq!(result[1][i], expected_lon, epsilon = 1e-7);
        }
    }
}